I think beside "Lock" and "Strong" we should have "Fixed" for maintaining those dimension even scaling model.
If user set the dimension to be fixed nothing can change the value - at the moment I obtain similar result using relations, but it works only after regeneration, but fixed dimension will remain the same always until user manually not change it.
yes as I described I do this, but it isn't so comfortable - that's because I vote for improvement.
I imagine if we'll have ability to set under context menu using just RMB "Fixed" option for selected via rectangle group of dimensions it'll be so easy in comparison to write for each dimension a correspond relation.
Current solution is painful - the new one will be a pleasure!